In communication systems in which information is encoded using transmission symbols from a transmission symbol set, such as Quadrature Amplitude Modulation (QAM) symbols or Quadrature Phase Shift Keying (QPSK) symbols from a QAM or QPSK constellation for instance, symbols in communication signals are detected and decoded at a receiver.
Although many transmission symbol detection techniques are known, these techniques are generally not feasible for communication systems in which multiple symbols are substantially concurrently received. Multiple Input Multiple Output (MIMO) communication systems represent one example of this type of communication system. The complexity of known techniques increases with both the size of a transmission symbol set and the number of symbols which are to be concurrently detected.
There are currently two kinds of MIMO decoding schemes, including Maximum Likelihood (ML) and Interference Cancellation (IC). ML decoders provide optimum performance, but ML decoder complexity increases exponentially with both the size of a transmission symbol set and the number of symbols which are to be concurrently detected. An IC decoder provides less satisfactory performance, but its complexity increases approximately linearly with both the size of a transmission symbol set and the number of symbols.